Bottom and bank facing

ABSTRACT

A bottom and bank facing for preventing erosion of subaqueous soil structures comprising a lattice of fascines fastened to a mat of synthetic resin material, wherein the resin material comprises a fabric sheet having means attached thereto for use in securing the fascines to the fabric, such means including transversely spaced groups of threads, each group being woven into the fabric at spaced portions along their length to provide resultant loops or floating portions in each group of threads to which the fascines are attached; or separate strips of fabric fastened to the fabric sheet for being tied to the fascines.

United States Patent 1191 De Winter 1111 3,811,287 1451 May21, 1974 BOTTOM AND BANK FACING [76] Inventor: Jan Gerrit De Winter, Lijsterstraat 18, Enschede, Netherlands [22] Filed: Aug. 10, 1971 [21] Appl. No.: 170,607

Related US. Application Data [63] Continuation-impart of Ser. No. 721,784, April 16,

1968, abandoned.

30] Foreign Application Priority Data Apr. 17, 1967 Netherlands 6705380 Nov. 2, 1967 Netherlands 6714909 [52] US. Cl 61/38, 161/48, 161/49, 161/50,161/53,161/ 78,161/89,161/91 [51] Int. C1.....'.... E02b 3/12 [58] Field 01' Search.... 161/48, 49,50, 53, 9.1,

[56] References Cited UNITED STATES PATENTS 1.371,451' 3/1921 ,Stacy 61/38 3,002,536 10/1961 Lord et a1, 161/91 3,142,109 7/1964 Stoll ct a1 161/91 3.150.029 9/1964 Ferrand, 161/95 FOREIGN PATENTS OR APPLICATIONS 1,216,889 12/1970- Great Britain 61/38 Primary Examiner-George F. Lesm es Assistant Exarhinew-Stanley S. Silverman Attorney, Agent, or Firm-Robert E. Burns 5 7] ABSTRACT A bottom and bank facing for preventing. erosion of subaqueous soil structures comprising a lattice of fascines fastened to a mat of synthetic resin material, wherein the resin material comprises a fabric sheet having means attached thereto for use in securing the fascines to the fabric, such meansincluding transversely spaced groups of threads, each group. being woven into the fabricat spaced portions along their length to provide resultant loops or floating portions in each group of threads to which the fascines are attached; or separate strips of fabric fastened to the fabric sheet for being tied to the fascines.

11 Claims, 4 Drawing Figures l BOTTOM AND BANK FACING This is a continuation-in-part of Ser. No. 721,784, filed Apr. 16, 1968, now abandoned.

This invention relates to facings for subaqueous soil structures, comprising fascines which cross each other according to a lattice pattern andare interconnected at the crossing points, and continuous fabric mat connected with said fascines. I

Conventional facings of this kind, known in the field of hydraulic engineering as mattresse's", comprise a bottom lattice formed from fascines, an upper lattice of fascines in register with said bottom lattice, and a center portion or filling consisting of a plurality of crosswise disposed layers of brush sandwiched between the two lattices. At the crossing points the fascines are interconnected with lashing, rope or like material, and in addition firm connections are made with this material between the crossing points of the bottom lattice and the superjacent crossing points of the upper lattice, so that the interposed filling is firmly retained therebetween.

A disadvantage of these known mattresses is that they require much material such as brush and reeds,

and a considerable ballast is required to compensate for the buoyancy of that .material when the facing is submerged. In addition, as a result of their'considerable height, the known mattresses are difficult to maneuver, and since the bottom lattice of fascines has a considerable thickness, the filling is prevented from contacting the bottom or bank at the portions along the fascines of the bottom lattice, thereby providing paths for water flow and resultant erosion. Also, the mattresses used hitherto are often insufficiently sand-tight.

It is an object of the present invention to provide a bottom and bank facing or revetment which obviates the above and similar disadvantages of known mattresses.

According to the present invention, there is provided facing for subaqueous soil structures, comprising fascines which cross each other according to a lattice pattern and are interconnected at the crossing points, and a continuous mat connected with said fascines, said mat consisting of a strong, slightly elastic, synthetic resin material, such as a fabric, whose sand-tightness, thickness, strength, and water-permeability are adapted to the requirements dictated by the soil conditions and the other conditions of the work. The-mat is secured to the fascines as by means of separate strips of the same material such as the mat,'said separate strips being fastened to the mat and tied around the fascines; or, by means of bands of threads which are woven into the mat at spaced portions along their lengths, thus providing unattached or floating portions of the threads in each band thereof to whichthe fascines may be secured.

It should be noted that the use of a mat as the filling of a mattress has already been proposed to replace the conventional brush and/or reed filling. In the prior proposal, however, the mat concemed is composed of an impermeable synthetic resin foil reinforced with a wire netting. in that known application the securing of the fascines to the mat filling is time-consuming and cumbersoine.

It should further be noted tliatthe use of synthetic resin netting is known per se for the protection of mounds of sand or earth, but not as a substitute for amply sufficient for the contemplated connections and fastenings.

mattresses and other submerged bottom or bank facmgs.

According to a preferred embodiment of the invention' the synthetic resin material engages portions of the fascines. That is, zones of the synthetic resin material constituting the mat proper extend in at least one of the directions of longitudinal extent of the fascines, and a group of threads are woven into each of said zones in bands of-a certain width on opposite sides of the axis of the fascine concerned, said threads being unattached to the inat -a't portions therealong to float jointly on the side of the mat facing the fascines in places spaced along the length of the band, said fascines being connected together and with the mat by means of rope or "like material, which is passed through the loops formed by the bundled floats on opposite sides of the fascines and across the fascines and thus tightened. v

According to the invention the floating bands of woven-in threads preferably have a color contrasting with the color of the mat, so that the lattice pattern-according to which the fascines must be laid in assembling the facing is clearly marked, while the loops formed by the floating thread portions, through which rope or other material is passedfor firmly connecting the fascines together and to the mat, become clearly visible. The rapid assembly of the mattress is thus effectively promoted. v When the lower fascines are laid transversely to the woven-in bands of synthetic threads it may be sufficient, by a suitable selectionof their spacing, to connect them with the mat at'the points where they are intersected by the upper fascines, while the upper fascines can be connected to themat through bundled floats at points intermediate said crossing points. However, the lower fascines may also be laid parallel to the.

woven-in bands of threads. In that case separate bands of threads may be woven in for the connection of the upper fascines with the mat between the crossing points with the lower fascines. These bands, conveniently extending parallel to the other bands, have floating por-.

tions at the places where they are intersected by the upper fascines. g

A typical example of a suitable material for the purposes of the present invention is a dobby fabric of polyethylene yam having a tensile strength of 3,000kg/m', and having additional threads, disposed in parallel, and partially woven therein in spaced groups, each group including'about 32 threadsarranged to provide a band of such threads which is about 2.2 cm. in width; said bands in each pair having their axes spaced at'about l 5 cm., and each pair of such bands beingspaced from the adjacent pairs by a distance corresponding to the distance between adjacent parallel fascines. Each of the threads is woven into the fabric at intervals spaced along its length so that it provides a loop or floating portion, such loops being disposed in parallel and each extending for about 10 cm for providing groups of thread loops to which the fascines may be attached.

in this arrangement, the loops constituted by .the

groups of floating portions of the threads are capable of holding tensile forces of at least l00kg, which is According to another embodiment of the invention, separate strips of the synthetic resin material referred to, such as a fabric, are attached to the mat for engaging a portion the circumference of the lower fascines in connections; and, the resin material is a polyethylene yarn fabric having a tensil strength of at least 2,000 kg/m'.

By tightening the rope material throughithe eyelets, in the manner described, the rope material comprising, for example, manilla rope or nylon cord, there is obtained a sturdy construction which requires relatively little ballast for it to be sunk. When the facing according to the invention is sunk, the mat fully beds down on the bottom or bank throughout its extent, so that there is no risk of the mattress being undermined. A special advantage is that the manufacture of the facing does not require a separate intertidal building site or slipway, since it can be made and payed out from a vessel orfrom the bank. The lattice to be formed from the fascines is secured, in the manner described, to the graduallyunrolled mat.

Of essential importance is also the fact that the mat does not require any brush; such material which is in short supply in some areas being required only for use in forming fascines, if required at all. The rate of production of the facings according to the invention is at least three to four times that of conventional mattresses, and a stock of the fascines can be made, and a facing can be rapidly assembled, as and whenrequired, mainly by unskilled labor. Skilled labor is only required for sinking the facing. In addition, the material used for the mat has a long service lifeas compared with conventional mattresses, since the fabric material .is resistant to corrosion.

A further advantage is that time is also saved in the sinking of the facing. In a similar period of time, considerably more facings can be positioned than has hitherto been possible. which is especially of importance with tidal currents. Also, no auxiliary structures are required at high water, as is the case with conventional mattresses. In cases in which a beddin'gmust be made for the fac'ingbyexcavation, an obvious advantage as com pared with the known mattresses is the small thickness of the'facing according to the invention, which materially reduces the excavation work required. A preferred feature of the embodiment of the invention provided with separate fastening strips is that washers of rubber or like material may be inserted around theeyelets so that the insertion of the connecting rope'material is thus considerably simplified, while thereis no risk of tearing when the connections are tightened. i

Another feature of the invention, which is a convenience in laying down the structure, is that the mat extends beyond at least one of the two extreme lower fascines to form a'projecting flap, the free terminal zone of which is weighted as with a length of reinforcing rod, such as used in reinforcing concrete, or the like, en-

closed in an endseam thereof. By. virtue of the flap it,

is possible to lay a plurality of such facingSin an overlapping relationship and hence closer together, thereby providing a sturdier revetment. The flap can also be useful during the transport ofthemattress, particularly by virtue of the weighting member accommodated therein, as will be described more fully hereinafter.

The invention will now be described in greater detail with reference to the accompanying drawings, which illustrate by way of example, two embodiments of a facing according to the invention.

In said drawings,

FIG. 1 is a plan view 'of a portion of a first embodiment of the invention;

FIG. 2 shows, on a larger scale, a part-sectional view on the line II-II in FIG. 1

FIG. 3 is a plan view of a portion of a second embodiment of the invention, with portions broken away; and,

FIG. 4 is a cross-sectional view on the line IIII in FIG. 3.

Referring to the drawings, there is shown a mat l of polyethylene yam dobby fabric having a tensile strength of 3,000 kg/m (that is to say, a length, of the fabric having a width of l m can carry tensile loads of up to 3,000 kg uniformly applied throughout its width). The mat is composed of a plurality of webs of the maximum width that can be woven, the webs being sewn together to a size which is common for facings, for example, 30 X 60m; The mat contains a plurality of longitudinally disposed groups of threads 2, each group forming a longitudinal band of about 2.2 cm, and each formed of32 polyethylene threads woven into the fabric of the mat (such as with a sewing machine) except at a plurality of places spaced along the length of the mat, where all of the threads in the group float freely I on the upper side of the mat as viewed in FIG. 1 for an extent of about 10 cm. These floating bundles of threads thus form loops '3, through which ropes can be inserted for securing fascines to the mat.

As shown in FIG. 1 the bands are woven in pairs at intervals spaced apart 50 cm transversely of the mat,

the axes of the bands of the-individual pairs being spaced a' distance of 15 cm. The loops formed by the floating thread portions are located at the points of intersection of the bands with an imaginary system of lines extending transversely of the mat. Thus, the lines in this system are disposed in a pattern of l5-50-l 5-50 cm etc., transversely of the mat. 1

As shown in the drawing, lower fascines 4 are laid in alignmentwith the middle of every other pair of bands on the mat l, and upper fascines 5 are laid transversely to these, spaced 1 m from each other. The axes of the crossing fascines thus form a lattice pattern of squares. At each crossing point the fascines are secured together and to the mat by ties 6, passing through the loops 3 and across the superposed fascines. At intermediate points the lower fascines are similarly tied to the mat by means of ties 7 passed through the loops 3 located opposite each other at these points, and the upper fascines are secured by ties 8 passing through the loops 3 of the pairs of bands on which no lower fascines have been laid. 4

With a pattern of bands similar to the'embodiment illustrated, it is naturally also possible to interchange the lower and upper fascines, and, with a greater distance of, for example, cm, between the center lines of the successive pairs, to lay an upper fascine between each pair of bands, which is then connected with the connected with the mat, as described above, at said points of intersection with the upper fascines.

FIG. 2 shows in detail how the material of the mat is pulled tight against the fascines by tightening the ties 6, 7 and 8.

In an alternative configuration, the spacing between the bands in each pair is omitted and the bands are moved together to provide a single band every 50 cm. transversely of the mat, each band comprising a group of 64 threads providing a 4.4 cm. band.

It has been found that a particularly preferable fabric for use in silty conditions comprises a dobby fabric consisting, in warp, of 0.3 mm diameter polyethylene monofilament yarn, varying from about 13 to l5 ends per cm; and, in weft, of an 840 to 1,000 denier multifilament yarn such as polyamide polyester or polypropylene, varying from to 14 ends per cm. Such a fabric is exceedingly strong and has, for example, a tensile strength in warp of 4,000 kg per meter, and a ,corresponding strength in weft of about 5,500 kg per meter. Strong means for fastening the fascines to the mat are provided by weaving threads into the fabric to provide bands about 4.4 cm. wide at a spacingof about 50 cm.,

each such band including 64 threads of polyethylene monofilaments of a color which contrasts with that of the fabric. As described above, the threads are woven in to provide floating portions extending for about 10 cm. and at equally spaced intervals along the bands. The loops which result from bundling the floating portions together when tying the fascines to the mat will sustain a tensile force in excess of 180 kg, thus providing adequate strength for the fascine fastenings.

For applications where a coarser soil structure is to be protected the mat preferably comprises a dobby fabric of 0.3 mm. diameter polyethylene monofilament yarn varying from 20 to 23 ends per cm. in warp, and 7 to 1] ends per cm in weft, thus providing a tensile strength in warp of 5,500 kg per meter, and 3,000 kg per meter in weft. The bands of threads may be provided as set forth in the above example. In any event, the bands of threads, in any of the above-described configurations, also provide a reinforcing function to further strengthen thefabric.

Referring to FIGS. 3 and 4, there is shown a mat 11 of a composition similar to that of the above-described mat shown in FIGS. 1 and 2. Sewn to the mat are aplurality of separate strips 12 of a material similar to that of the mat fabric, said strips having a width of 25 cm and being folded upon themselves along their longitudinal edges to form an overlap or doubling of about 4 cm. The strips 12 are spaced apart about '1 m and are stitched to the webs of fabric comprising the mat by means of two-needle stitchings extending transversely of the mat, across the full width thereof. On one end of the mat a strip 12 is provided adjacent to the edge, and on the other end the last strip is spaced about 1 m from the edge to leave a flap 14 about 1 m wide, the flap having a seam formed at its terminal edge to receive a length of iron 15 such as a reinforcing rod for concrete or other suitable weighting member. Eyelets 16 are provided in the double longitudinal margins of the strips 12 at the points indicated in FIG. 3, and rubber washers are inserted between the fabric and the eyelets. Previously prepared fascines 17 are laid on the strips 12 and comprise the lower fascines of the lattice to be formed. Across these lowerfascines 17 are laid upper fascines l8, i.e., longitudinally of the mat, also spaced about I m from each other. The upper fascines 18 cross the lower fascines at places where four eyelets are fastened in the margins of the strips 12. Strips 19, about 40 cm long and otherwise similar in material and design to the strips 12, are sewn to the mat, also by. two-needle stitchings 20, between the points of intersection of each upper fascine with two successive lower fascines 17, with eyelets 21, similar to the eyelets l6, and rubber washers are provided centrally opposite each other in the margins of the strips. At the points of intersection of the fascines, and the points intermediate these points of intersection, the strips 12 and 19-are firmly lashed together by means of strong nylon cord inserted through the eyelets l6 and 21, so that the strips 12 and 19 embrace part of the circumference of the lower fascines l7 and the upper fascines 18, respectively. The extreme eyelets 16 are disposed adjacentto the longitudinal edges of the mat 11.

FIG. 4 shows that the mat 11 is pulled against the upper fascines at least in the intermediate zone be tween each pair of adjacent lower fascines.

In FIG. 4, the direction of current flow is indicated by an arrow A. By virtue of the weighting member 15,

the flap 14 of the mat 11 will hang down and thus enable utilization of the current in transporting thevfloating facing to its destination. It will be seen that the flap 14 will assume a bulging shape. V

The firm connections between the mat and the fascines, which are further strengthened by the partially surrounding strips and the lash connections, are productive of a sturdy facing which nevertheless is light in weight and low in buoyancy, so that relatively little ballast is required for sinking the mattress. Accordingly, a largev proportion of the overall ballast acts as actual weighting ballast on the facing when it is deposited on the bottom or bank.

Other modifications and changes will be readily apparent to those skilled in the, art, and can be made without departing from the scope of the invention as defined by the following claims.

What I claim is:

1. A bottom and bank facing for preventing erosion of subaqueous soil structures on which it is placed 'comprising a strong, slightly elastic, sandtight, water permeable continuous mat of synthetic resin fabric lying on the soil surface to be protected, a lattice of fascines superposed on said mat and comprising a set of spaced parallel lower fascines disposed on said mat and a set of spaced parallel upper fascines overlying said lower fascines and crossing said lower fascines substantially at right angles, said mat having on its upper surface at each crossing of said upper and lower lattices and intermediate said crossings receiving means connected-with said mat and providing openings to receive tying material, and strands of tying material passing over said fascines and through respective openings of said receiving means at each said crossing and intermediate said crossings to secure the crossing fascines to one another and to secure said fascines in said mat, said strands of tying material passing through said openings of said receiving means without passing to the lower side of said mat and thereby avoiding discontinuities in the fabric of said mat, said fascines being disposed solely on the upper face of said mat whereby said mat lies on the surface of the soil to be protected without fascines therebetween, thereby avoiding undermining of the facing.

2. A facing according to claim 1, wherein the synthetic resin material fabric is a fabric of polyethylene yarn, said fabric having a tensile strength of at least 2,000 kg/m.

3. A facing as set forth in claim 1, in which said receiving means comprises a plurality of elongated spaced groups of threads disposed in parallel and woven into said synthetic resin fabric only at transversely aligned intermittent portions along the extent of said threads, thereby providing floating portions of said threads between said intermittent portions, one of said sets of fascines being disposed in alignment with said groups of parallelthreads, and in which said strands of tying material for securing said fascines to said mat pass under said floating portion of said groups of threads and over said fascines.

y 4. A facing according to claim 3, in which said groups wise of a second coior which contrasts with said first color. 7

5. A facing as set forth in claim 1, in which said receiving means comprises a plurality of separate strip means of synthetic resin fabric attached to said mat for enclosing at least a portion of the circumference of said .lower fascines along a substantial. longitudinal extent 7. A facing asset forth in claim 1', in which the spac- "of threads are of a first color, and said fabric is otherfascines are disposed longitudinally in a common plane below said upper fascines, and in which said mat is dis-- posed in continuous contact with said lowerfascines along the entire longitudinal coincident extent of said mat and said lower fascines.

10. A facing as set forth in claim 9, in which the synthetic resin fabric is a fabric comprising polyethylene yarn, said fabric having a tensile strength of at least 2,000 kg/m', and further comprising a plurality of elongated spaced groups of threads disposed in parallel and woven into saidfabric only at transversely aligned intermittent portions along the extent of said threads, the

fascines of one of said sets of fascines being disposed in alignment with said respective groups of threads, and in which said strands of tying material for securing said fascines to said mat pass under said floating portion of said group of threads and over said fascines.

11. A facing as set forth in claim 10, in which said polyethylene yarn is disposed in the-warp in said fabric, said fabric further comprising weft yarnselected from the group consisting of polyainide polyester or'polypropylene. s 

1. A bottom and bank facing for preventing erosion of subaqueous soil structures on which it is placed comprising a strong, slightly elastic, sandtight, water permeable continuous mat of synthetic resin fabric lying on the soil surface to be protected, a lattice of fascines superposed on said mat and comprising a set of spaced parallel lower fascines disposed on said mat and a set of spaced parallel upper fascines overlying said lower fascines and crossing said lower fascines substantially at right angles, said mat having on its upper surface at each crossing of said upper and lower lattices and intermediate said crossings receiving means connected with said mat and providing openings to receive tying material, and strands of tying material passing over said fascines and through respective openings of said receiving means at each said crossing and intermediate said crossings to secure the crossing fascines to one another and to secure said fascines in said mat, said strands of tying material passing through said openings of said receiving means without passing to the lower side of said mat and thereby avoiding discontinuities in the fabric of said mat, said fascines being disposed solely on the upper face of said mat whereby said mat lies on the surface of the soil to be protected without fascines therebetween, thereby avoiding undermining of the facing.
 2. A facing according to claim 1, wherein the synthetic resin material fabric is a fabric of polyethylene yarn, said fabric having a tensile strength of at least 2,000 kg/m.
 3. A facing as set forth in claim 1, in which said receiving means comprises a plurality of elongated spaced groups of threads disposed in parallel and woven into said synthetic resin fabric only at transversely aligned intermittent portions along the extent of said threads, thereby providing floating portions of said threads between said intermittent portions, one of said sets of fascines being disposed in alignment with said groups of parallel threads, and in which said strands of tying material for securing said fascines to said mat pass under said floating portion of said groups of threads and over said fascines.
 4. A facing according to claim 3, in which said groups of threads are of a first color, and said fabric is otherwise of a second color which contrasts with said first color.
 5. A facing as set forth in claim 1, in which said receiving means comprises a plurality of separate strip means of synthetic resin fabric attached to said mat for enclosing at least a portion of the circumference of said lower fascines along a substantial longitudinal extent thereof, and for enclosing spaced portions of said upper fascines, and means for securing said strip means to said mat, said strip means having eyelets therein to receive said strands of tying material passing through said eyelets and over said fascines.
 6. A facing according to claim 5, wherein the strip means are sewn to the mat.
 7. A facing as set forth in claim 1, in which the spacing between said parallel fascines is of the orDer of three quarters to 1 meter.
 8. A facing as set forth in claim 1, in which said mat extends beyond at least one of the two outermost fascines in one of said sets of fascines and is folded back to form a flap, and further comprising means attaching the edge of said flap to said mat to provide pocket means for holding a ballast weight.
 9. A facing as set forth in claim 1, in which said lower fascines are disposed longitudinally in a common plane below said upper fascines, and in which said mat is disposed in continuous contact with said lower fascines along the entire longitudinal coincident extent of said mat and said lower fascines.
 10. A facing as set forth in claim 9, in which the synthetic resin fabric is a fabric comprising polyethylene yarn, said fabric having a tensile strength of at least 2,000 kg/m'', and further comprising a plurality of elongated spaced groups of threads disposed in parallel and woven into said fabric only at transversely aligned intermittent portions along the extent of said threads, the fascines of one of said sets of fascines being disposed in alignment with said respective groups of threads, and in which said strands of tying material for securing said fascines to said mat pass under said floating portion of said group of threads and over said fascines.
 11. A facing as set forth in claim 10, in which said polyethylene yarn is disposed in the warp in said fabric, said fabric further comprising weft yarn selected from the group consisting of polyamide polyester or polypropylene. 